This bill would significantly limit the president's power to designate national monuments under the Antiquities Act. Currently, presidents can create monuments that remain in place indefinitely, but this legislation would require all new monument designations to expire after six months or at the end of the congressional session, whichever comes first, unless Congress passes legislation to extend or modify them. If Congress does not approve an extension during that window, the same land cannot be designated as a monument again for 25 years. The bill affects the president's executive authority and applies to all future national monument designations under this act. No specific funding is mentioned in the legislation, as it primarily restructures the approval process for monument designations rather than allocating resources.